DE2428820B2 - PROCESS FOR THE PRODUCTION OF ISOPENTEN - Google Patents

Description

55

The invention relates to a process for the production of 1 isopentene by catalytic disproportionation it isobutene and η-butene-containing hydrocarbon mixture.

} he term "isopentene" includes 2-methylbutene-1, 1-ethylbutene-2, 3-methylbutene-1 or mixtures 1 two or more of these compounds.

) the term "η-butene" includes cis-butene-2, transien-2, Butene-1 or mixtures of two or more of these butenes.

It is known that olefins are disproportionated by using a molybdenum-alumina catalyst be brought into contact. However, it is also known that when the usual disproportionation method applied to olefin mixtures using a molybdenum-alumina catalyst which are mainly hydrocarbons with 4 carbon atoms such as isobutene and n-butene The following disadvantages occur:

(1) Low disproportionation turnover

The expression "disproportionation turnover" refers to the present ratio of the weight of the Disproportionation product to the original weight of the hydrocarbon mixture that the Is subjected to disproportionation process.

(2) Low proportion of the C ₅ fraction
in the resulting disproportionation product

The term "Cs faction" refers to a Distillate fraction consisting essentially of hydrocarbons with 5 carbon atoms and of the Disprop'ortionierungsprodukt has been separated

(3) High proportion of the C _{+ 6} fraction
in the disproportionation product

The term "C + 6 faction" refers to a Distillate fraction consisting essentially of hydrocarbons with 6 or more carbon atoms and which has been separated from the disproportionation product.

(4) Low isopentene content in the C5 fraction

It thus follows that the previously customary process for the preparation of isopentene on the way of Disproportionation is only of subordinate industrial importance. This arises in particular from the following reference example 1.

In the usual disproportionation of olefin using a usual catalyst, for example a molybdenum-aluminum catalyst, it is known that the supply of steam to the Disproportionation reaction system leads to a considerable decrease in the disproportionation conversion leads. This results essentially from Reference Example 2 below.

In US-PS 35 44 648 and 35 46 314 processes for converting an olefin to other olefins are with changed numbers of carbon atoms described by bringing the olefin into contact with a catalyst that is capable. To disproportionate propylene to ethylene and butene. The catalyst consists of tungsten oxide and silicon oxide.

If you have an isobutene and η-butene-containing hydrocarbon mixture in the presence of a tungsten oxide-silicon oxide catalyst disproportionated to produce isopentene, practically no disproportionation reaction takes place at a temperature between 220 and 380 ° C instead of. If you disproportionate at a temperature above 380 ° C, the yield is on The resulting isopentene is only very slight, as can be seen from the comparative examples 9 to 11 below.

The invention is based on the object of creating a method with which with high yield

Isopentene can be generated by disproportionation of an isobutene-endn-butene-containing hydrocarbon mixture, the carbon water? can be portioned with a high conversion rate, and the resulting disproportionation product _{contains a high proportion of the C 5} fraction, which in turn has a high proportion of isopentene! tufweise.

To solve this problem, the process according to the invention is characterized in that the hydrocarbon mixture is mixed with a catalyst which is produced by introducing a molybdenum compound and at least one further cobalt, tin, silver, zinc, cadmium, lead, bismuth or an antimony compound on an aluminum oxide support and subsequent calcination and which is made up of 5–20% of the calcined molybdenum compound and 0.5–10% of the calcined additional metal compound, based on the weight of the aluminum support and based on the corresponding oxides, consists, in the presence of 0.1-25% water vapor, based on the volume of the hydrocarbon mixture and calculated on normal volume, with a flow rate of 50-2000 cmVh, calculated on normal volume, per cm ^{3 of} the catalyst in contact and at a temperature of 220 ° -380 ° C and a pressure between normal pressure and 10 kg / cm ² disproportionate and the isopentene formed a separated from the reaction mixture.

When the process according to the invention is used, the disproportionation product contains a relatively high proportion of propylene, a relatively high proportion of the Cv fraction and a relatively low proportion of the C _{+ b} fraction, these fractions consisting of olefin compounds. The disproportionation product obtained thus contains a high proportion of the very valuable substances propylene and the Cy fractions.

The disproportionation step may lead to dimerization and isomerization of a smaller one Part of the hydrocarbon mixture lead, while the greater part of the hydrocarbon mixture is disproportionate.

If the amount of water vapor is below 0.1% by volume, undesired side reactions occur, for example isobutylene is diminished. As a result of such undesired side _{reactions, the proportion of the C +6} fraction in the disproportionation product is undesirably increased, as a result of which the isopentene proportion in the C5 fraction decreases come.

It is preferred to disproportionate in the presence of an amount of 0.2-10% water vapor, based on the volume of the hydrocarbon mixture and calculated to the normal volume size.

A disproportionation ^{temperature below 220 °} C. leads to an undesirably high proportion of the C + 6 fraction in the disproportionation product. A disproportionation temperature above 380 ° C. leads to an undesirably low ratio of the disproportionation conversion, to a shortened service life of the catalyst and to increased decomposition of the hydrocarbon mixture. It is preferable to disproportionate at a temperature of 230-350 ° C.

Been According to a further embodiment of the method of the invention is disproportionated in the presence of a catalyst which contains .- at a temperature of 100-300 ⁰ C with an inert gas, calculated on volume standard, 0.1 -25 Vo!% Steam treated is. This treatment leads to an improvement in the initial activity of the catalyst, and the result obtained is evident from Example 2 below.

The hydrocarbon mixture is preferably brought into contact with the catalyst at a flow rate between 100 and 1000 cm ³ / cm ^{3 catalyst / hour}

The catalysts used for carrying out the process according to the invention are in the Way produced that a molybdenum compound and at least one further metal compound from the Group of cobalt, tin, silver, zinc, cadmium, lead, bismuth and antimony compounds on one Alumina or alumina carrier deposited and the compounds deposited on the alumina carrier to be calcined.

An additional metal compound is halides, sulfates, nitrates, carbonates, Hydroxides, oxides, hydroxy carbonates and organic acid salts of cobalt, tin, silver. Zinc, cadmium, Lead, bismuth and antimony.

The cobalt compound can be cobalt chloride, Cobalt nitrate, cobalt sulfate, cobalt acetate, cobalt format, cobalt oxalate, cobalt hydroxide, cobalt carbonate or cobalt oxide.

Tin (H) chloride (stannous chloride), tin (II) bromide, tin (H) oxide, Use tin (II) nitrate or tin (II) acetate.

The silver compound used to make the catalyst can be Silver chloride, silver bromide, silver nitrate, silver carbonate, Act silver oxalate, silver oxide or silver hydroxide.

The zinc compound is in particular zinc chloride, zinc bromide, zinc sulfate, zinc nitrate, Zinc carbonate, zinc oxalate, zinc acetate or zinc oxide.

The cadmium compound is in particular cadmium chloride, cadmium nitrate, cadmium sulfate. Cadmium carbonate, cadmium oxide, cadmium acetate or cadmium oxalate.

The lead compound is in particular around lead chloride, lead nitrate, lead sulfate, lead carbonate, lead hydroxide, lead hydroxycarbonate, lead oxide, lead acetate and lead format.

The bismuth component used is in particular bismuth chloride, bismuth nitrate, Bismuth sulfate, bismuth hydroxy carbonate, bismuth oxide or bismuth itoxalate.

The antimony compound used is in particular antimony chloride, antimony sulfate, Antimony hydroxide or antimony oxide.

In the production of the catalyst used molybdenum compound is in particular such molybdenum compounds, the usual catalysts already used in the known processes have been used, preferably molybdenum oxide, ammonium molybdate, molybdenum chloride or Molybdenum oxychloride.

In the case of the aluminum oxide, which is used as a carrier for the production of the catalyst according to the invention is in particular activated aluminum oxide, in particular γ-aluminum oxide and ■ jj-aluminum oxide. This alumina has that usual structure, as in the known catalytic converter

ren is present

The alumina supports used for the catalyst of the present invention are very small Grain size corresponding to a screen size of 2-100 mesh, preferably 4-50 mesh

The molybdenum compound and the additional metal compound can be on the aluminum oxide carrier deposited by known methods, for example using the co-precipitation method, in which both the molybdenum compound and the additional metal compound as well as a Aluminum compound are simultaneously precipitated from an appropriate solution; it can also after the impregnation method are used in which the aluminum oxide is impregnated with a solution of the molybdenum and additional metal compound and is then dried.

If the impregnation method is used, the molybdenum compound and the additional metal compound can be deposited on the aluminum oxide carrier at the same time or in any order. For example, the molybdenum compound can be deposited on the alumina and calcined to remove the water absorbed by the alumina before one or more of the additional metal compounds are deposited on the molybdenum compound already deposited on the alumina and calcined to produce the inventive catalyst. However, it is also possible to deposit the additional metal compound on a commercially available molybdenum-aluminum oxide catalyst. The molybdenum compound and the additional metal compound have been deposited on the alumina support, be 3-10 hours at a temperature of 300-1000 ⁰ C, preferably 5OO-7OO ° C, calcined in a stream of air or nitrogen stream, a common Kalziniermethode applied and, for example, an electric furnace is used.

The isobutene content in the hydrocarbon mixture is preferably above 30% by weight, preferably between 30-60% by weight. The η-butene can contain 1-butene. With common butene disproportionation processes it is known that the 1-butene content in the hydrocarbon mixture increases in the course of the disproportionation stage leads to an undesirable increase in the n-pentene content in the C5 fraction of the process according to the invention, however, becomes that in the hydrocarbon mixture butene-1 contained isomerized to butene-2 and at the same time disproportionated, so that the undesired Formation of n-pentene is very low. The Cs fraction formed according to the invention thus contains a very high proportion of isopentene, i.e. the C ^ fraction consists essentially of isopentene.

The hydrocarbon mixture used can also contain other components than isobutene and n-butene contain the same hydrocarbons such as n-butene, isobutene, propylene, propane, 1,3-butadiene, isopentane, Isopentene, isoprene, n-pentane and n-pentenes. The total proportion of these other hydrocarbons that are present in the hydrocarbon mixture used, should preferably not be higher than Be 15% by weight. The proportion of conjugated diene compounds, for example 1,3-butadiene and isoprene, should preferably 1.0 wt% or less.

A so-called RB fraction can be used as the hydrocarbon mixture, which is is an extraction residue, which is produced by U-butadiene from a distillate fraction is extracted, which consists of hydrocarbons with 4 carbon atoms (C fraction) and by thermal decomposition or catalytic cracking of natural gas, petroleum gas, naphtha or any other Petroleum fraction has been produced

The manner in which steam is supplied during the disproportionation process can be carried out in the usual way, but this steam supply must take place at a constant rate. According to one procedure, the hydrocarbon mixture is allowed to flow through a water bath which is kept at a predetermined temperature so that a certain amount of water is evaporated and mixed with the hydrocarbon mixture at a predetermined rate. According to another procedure, the hydrocarbon mixture is admixed with a certain amount of steam which has previously been generated in another way. According to another method, ^"1 -eise allowed to the hydrocarbon mixture along the surface of a water bath flow, which has a suitable temperature so that the hydrocarbon mixture is mixed with the vaporized from the water vapor. The hydrocarbon mixture containing a sufficient amount of steam is then brought into contact with the catalyst

According to a further procedure, the hydrocarbon mixture is converted into an aqueous solution initiated which is saturated with a metal salt, which keeps the vapor pressure of the solution constant; as Examples are calcium chloride, potassium bromide, zinc sulfal and magnesium nitrate. The mix of Steam and hydrocarbon mixture are then brought into contact with the catalyst.

The process according to the invention is described in more detail below with reference to the examples.

In the following examples, reference examples and comparative examples, the composition of the Disproportionation product determined in the manner described in each case. After completion of the disproportionation process, the reaction mixture was subjected to gas chromatography analysis subjected to determine the amounts of the individual hydrocarbon components in the reaction mixture and record. From the record of gas chromatography analysis to the analysis results contains all of the compound components in the reaction mixture, the analysis results of the hydrocarbon representing the disproportionation product from the analysis results of the non reacted hydrocarbons isolated that were still in the reaction mixture.

From the isolated analysis results, the proportions of the hydrocarbon components in the disproportionation product were calculated in percent based on the mixture of the disproportionation product. The proportions of the Cs fraction and the C + «fraction were also derived from the result of the gas chromatographic analysis in the same manner as described above. The isopentene content was calculated on the basis of the weight of the C _{5 fraction.} The disproportionation conversion ratio was calculated as a percentage ratio of the weight of the disproportionation product to the original weight of the hydrocarbon mixture which was subjected to the disproportionation process.

must

Reference example 1

Production of isopentene with a catalyst made from molybdenum compound deposited on an aluminum oxide support

To prepare a catalyst, y-aluminum oxide, which corresponded to a sieve size of 14-32 mesh (ASTM), was impregnated with an aqueous ammonium molybdate solution having an ammonium molybdate content of 5% by weight, dried and then for 4 hours in a stream of air at a temperature of 400 ⁰ C calcined. The resulting catalyst had a composition of 92.5% by weight of alumina and 7.5% by weight of calcined molybdenum compound, calculated as molybdenum oxide. ι s

A BB gas fraction which consists of 48.7% by weight of isobutene, 16.4% by weight of butene-2, 26.3% by weight of butene-1, 1.2% by weight of isobutane, 7.1% by weight of isobutane. -% η-butane and a total of 0.3% by weight propane, propylene, 1.3 butadiene and propadiene, was under normal pressure at: io a temperature of 250 ° C with 6 cm ³ catalyst with a flow rate of 500 cmVcm ³ Catalyst / hour brought into contact to cause the disproportionation of the BB fraction.

In Table 1, the disproportionation conversion ratio of the above process is the proportion of the resulting

Table 1

Reference- Disproportionie- Disproportionie- Isopcnlenanieil in the composition of the Disproportionierungs-

sample time sample turnover Cs fraction producles (%)

Propylene Cv fraction C 1 el'raktion

the isopentene in the CV fraction and the composition of the disproportionation product after 1.5 and 2.5 hours after the start of the Disproportionation process reproduced.

Reference example 2

Production of isopentene in the presence of steam using the same catalyst as in

Reference example 1

The same steps as in Reference Example 1 were repeated, except that the BB gas fraction used was passed through a water bath ^{kept at a temperature of 0} ° C. by being cooled under normal pressure so that 0.6 vol. -% water, based on normal volume under standard conditions, ie O ⁰ C and 760 mm Hg, were mixed with the BB gas fraction.

In Table 1 are the results of this proportioning process shown, namely the disproportionate conversion rate, the content of the resulting isopentene in the Cs fraction and the composition of the disproportionation product after a period of time from 1.5 and 2.5 hours after the start of the disproportionation process.

1 1.5 23.8 65.0 34.4 38.1 25.9 2.5 16.8 59.0 28.3 40.1 30.2 2 1.5 13.6 94.2 25.4 44.9 26.7 2.5 12.8 96.2 28.3 45.3 25.9

Remarks:

The disproportionation products according to reference examples 1 and 2 contain a small amount of ethylene,

C '·: Mixture of hydrocarbons with 5 carbon atoms each. C + 6: Mixture of hydrocarbons with 6 or more carbon atoms.

It can be seen from Table 1 that when a molybdenum-aluminum oxide catalyst system is used the application of steam leads to a decrease in the disproportionation conversion, while the proportion the Cv fraction in the disproportionation product and the isopentene fraction in the CV fraction grows.

example 1

To produce a catalyst, γ-aluminum oxide was used with a grain size corresponding to a sieve size of 14 bn Ϊ2 Me% h with an aqueous ammonium oxide. which contains 5% by weight of ammonium molybdate. rmpragniert, dried for 4 hours in a ert! "ftttrom at a temperature of 400 C ^e kal7fti" Since »m and impregnated this way fcal / mierfe material was flfiratltoung with an aqueous cobalt. which contained 4% by weight of cobalt nitrate, impregnated, dried and calcined for 4 hours in an iMtiMuim at 600 "C. The resulting material was impregnated with an aqueous solution of 0% by weight of tin (II) chloride, dried and then for 34 hours in one Air stream calcined at a temperature of 600 ° C. The esltierede catalyst consisted of 923 parts by weight of aluminum oxide, 1 part by weight of zincated tin compound, calculated as tin oxide (SnO), 2 parts by weight of calcined cobalt compound, calculated as cobalt oxide (CoO) unc 73 parts by weight of calcined molybdenum compound, calculated as molybdenum oxide (MoO ₃ ).

The same BB gas fraction as in the reference example 1 was passed through a water bath which was kept at a temperature of 0 ° C by cooling under normal pressure, so that the BB gas fraction was 0.6% by volume of steam, based on normal volume <under standard conditions, was mixed; the mi steam mixed BB-gas fraction was mixed with 6 cm ¹ de-prepared catalyst under normal pressure be a temperature of 250 "C is brought into contact un the disproportionation of the BB fraction to effect the fraction with a flows ngsgeschwindig) speed of SOOcmVcm ³ Katarysator / Hour supplied and based on normal volume In table 2 the results of this disproportionation are shown: i.e. the disproportionation conversion, the isopentenic content in the Cv fraction and the composition of the resulting disproportionation duration after a period of 15.25.35 and 45 hours after the start of the disproportionate process.

Table 2

Disproportionie- Disproportionie- lsopentengehali Composition of the disproportionation product (%)

sales time in the Cs fraction

Propylene Cs fraction C + b fraction

1.5 26.5 100 32.7 49.3 18.0 2.5 24.5 100 34.1 52.6 13.3 3.5 22.4 100 33.5 53.1 13.3 4.5 22.2 100 32.9 55.0 12.1

A comparison of Table 2 with Table 1 clearly shows that the inventive method the Process according to reference examples 1 and 2 with regard to the disproportionation conversion ratio, of the Cs fraction in the disproportionation product and the isopentene content in the Cs fraction is superior. It is particularly worth mentioning that when comparing the present example with reference example 2, the use of cobalt and tin compounds as components of the catalyst to an increase in the disproportionate

Table 3

tion conversion, the C ₅ fraction in the disproportionation product and the isopentene in the C ₅ fraction leads.

Comparative example 1

The same process steps as in Example 1 were repeated, but the BB gas fraction was brought into contact directly with the catalyst without first being passed through the water bath. The results are shown in Table 3.

Disproportionation time

(Hours.)

Disproportionate turnover

Isopentene content of C5 fraction

Composition of the disproportionation product (%)
Propylene Cs fraction C + b fraction

1.5 14.3 90.5 25.9 47.6 26.3 2.5 13.2 94.6 34.2 44.0 21.7

Note: The disproportionation product contained a small amount of ethylene.

A comparison of Tables 3 and 2 shows that the absence of steam during the disproportionation process to a decrease in the disproportionation turnover, the Q fraction fraction in the disproportionation product and the isopentene content in the C5 fraction.

Examples 2, 3 and 4 and Comparative example 2

In Example 2, the same steps as in Example 1 were repeated, except that the same catalyst as in Example 1 was subjected to steam treatment by using a mixed gas of nitrogen and 0.6% steam based on the nitrogen volume and based on normal volume for 30 min . At a temperature of 250 ⁰ C with a catalyst at a flow rate of 1000 cmVcm ³ catalyst

TabeHe 4

35 gates / hour was brought into contact. The results are shown in Table 4.

In Example 3, the same steps were repeated as in Example 1, but the disproportionation process was carried out at a temperature of 300 ^{° C. instead of 250 ° C.} The results are in

Table 4 reproduced.

In Comparative Example 2, the same steps were repeated as in Example 1, except that the Disproportionierungstemperatur not was 250 ⁰ C but 2O0 ° C. The results are in Table 4

reproduced.

In Example 4, the same steps as in Example 1 were repeated, but the flow rate or feed rate of the same BB gas fraction as in Example 1 1000 cmVcm ³ catalyst / hour. fraud,

in relation to normal volume. The results are shown in Table 4 .

Bet game no. Flow
1 · j- Dispropor Disproportionate Disproportionate Isopentes Composition of Disproportionate 16.1 swiftly tioning tioning tioning salary in the production product i%) 14.6 speed d coals temperature Time sales Cs Group 12.6 hydrogen
mixed Propjrlen Cs fraction C + 6 fraction 13.1 cmVcm ³ kata 41.9 analyzer / hour TQ (Hours) (%) (%) \ Δ.Κ Example 2 500 250 03 23.1 100 29.8 54.1 13th 253 100 30.8 54.6 23 23.0 100 322 55.2 Example 3 500 300 13th 12.6 100 36.0 Comparison
example 2 500 200 13th 12.1 100 18.7 39.2 Example 4 1000 250 33 14.2 100 30.7

Examples 5 to 10

For each of Examples 5 to 10, a catalyst with the composition given in Table 5 was used using the same procedure as in Example 1. The amount of calcined Metal compounds in the catalysts was considered a

the metal oxide corresponding to the metal compound is calculated. It was the same procedural steps as repeated in Example 1, using the catalysts specified in each case. The results of the Disproportionation process as it occurs after a period of 3.5 hours from the start of the process are shown in Table 5.

Tabel 5 CoO of the catalyst AIiOi Disproportionate Isopentengehali Composition of the disposition Cs fractional ι C + b group example 3.5 86.5 tioning in the nation product (%) 53.3 15.1 No. composition 3.5 86.5 salted Ci Fraklion 54.5 15.0 (Weight parts) 3.5 MoOj 86.5 W. (%) Propylene 51.6 14.6 3.5 10 86.5 19.3 100 31.6 55.5 13.2 5 SnO 0 10 92.5 19.1 100 30.4 53.3 15.6 6th 0.8 3.5 10 86.5 21.3 100 33.9 46.1 22.2 7th 1.0 10 19.4 100 31.2 8th 1.3 7.5 21.7 100 31.0 9 2.7 10 17.9 100 30.6 10 1.0 0

Comparative example 3

The same steps as in Example 10 were repeated, but the BB gas fraction was brought into direct contact with the catalyst without this gas fraction having been passed through cold water at a temperature of ⁰ ° C. After a period of 3.5 hours after the start of the disproportionation process, the disproportionation conversion ratio was 10.3%, the isopentene content in the Cs fraction was 68.8% and the disproportionation product contained 29.8% propylene, 32.2% of the Cs fraction , 34.2% of the C ₊₆ fraction and 3.7% ethylene.

Examples 11-14 and
Comparative example 4

In Examples 11 to 14, four catalysts with the compositions shown in Table 6 were prepared by impregnating γ-alumina with a grain size corresponding to a screen size of 14-32 mesh with an aqueous ammonium molybdate solution, drying and 4 hours in a stream of air calcined at a temperature of 400 ⁰ C. Then the γ-aluminum oxide impregnated and calcined in the above manner was further impregnated with an aqueous silver nitrate solution, dried and then calcined ^{in a stream of air at a temperature of 600 ° C. for 3.5 hours.} The same process steps as in Example 1 were repeated using the catalysts shown in Table 6. The disproportionation time was 3.5 hours. The results are shown in Table 6.

In Comparative Example 4, the same became

Process steps repeated as in Example 11, wherein however, the disproportionation process was carried out without steam. The results are also in Table 6 reproduced.

Table 6

Example No. Composition of the disproportionate

Kataiysators (parts by weight) sales turnover AgO Μοθ3 ΑΙ2Ο3

Isopentengehali
in the Cs group

Composition of the disproportionate

nation product (%)

Propylene Cs fraction C + b fraction

11th 1 7.5 923 22.6 100 30.6 453 23 ^ 12th 2 73 923 21.6 100 31.6 543 14.1 13th 4th 73 923 23.1 100 31.2 55.6 13.2 14th 6th 73 923 22.1 100 31.1 493 19.1 Comparison 1 73 923 113 82.4 273 40.2 323 example 4

From Table 6 it can be seen that the absence of Steam during disproportionation leads to a considerable decrease in the disproportionate turnover, des isopenten content in the Cs fraction and the Q fraction hook in the disproportionation product leads

Examples 15 and 16 Example 15 followed the same procedure te carried out as in Example 12. However, with the To prepare the catalyst, zinc nitrate was used instead of silver nitrate.

In Example 16, the same steps were carried out as in Example 6 Preparation of the catalyst instead of Zmn (H) chloride zinc nitrate was used.

The results of Examples 15 and 16 are in Table 7 reproduced.

Table 7

Example catalyst
No.

Disproportionate

tion time

(Hours.)

Disproportionate

tioning

sales of isopentrance in the
Cs group

(0/0) Composition of the disproportionate ionization product (° / o)

Propylene Cv fraction C + b fraction

15 Zn-Mo-AhCb

16 Zn-Co-Mo-AhCb

23
1.5
2.5
3.5
43

19.8 17.1 25.5 25.5 23.1 22.7

100

100 95.2 99.8

100

100 28.3
29.9
32.7
34.3
32.2
31.6

47.3
48.8
51.4
52.4
55.3
55.2

24.4 21.3 15.9 13.3 12.5 13.2

Comparative example 5

The procedure was the same as in Example 15, except that the use of steam was dispensed with. After a period of 3.5 hours after the start of the disproportionation process, the disproportionation conversion was 11.4% and the isopentene content in the Cs fraction was 663%, while the disproportionation product was 24.4% propylene, 42.0% in the C ₅ fraction and Contained 32.2% of the C ₊₆ fraction.

Examples 17 to 19 The process steps according to example

20th

_ became

repeated three times, but using the water bath through which the BB gas fraction was passed in Table 8 had temperatures indicated; the BB gas fraction contained after flowing through the water bath Steam in the amounts given in Table 8. The results are also in Table 8 listed.

Table 8 Example no.

temperature
of the water bath

Steam- Dispropor- Dispropor- Isopentene- Composition of the disproportionio-

Content of the tioning content of the production product (%)

Coal time conversion of Cs fraction

Hydrogen propylene Cs fraction C -.- β-fraction

weight

17 25

18 40

19 60

3.1

19.7

2.5 3.5

23 33 13 23 33

22.4 21.1 24.1

20.4 18.6 17.8

100 100 100 100 100 100 100 30.3
31.6
31.2
32.0
29.2
34.0
32.3

53.6 54.7
52.7 53.9 54.9 51.8 53.8

16.4 13.7 16.1 14.1 15.9 14.2 13.9

Example 20 and Comparative Example 6

A catalyst was prepared by impregnating γ-aluminum oxide with a particle size corresponding to a sieve size of 14-32 Mesk with an aqueous ammonium molybdate solution containing 5% by weight of ammonium molybdate, impregnating it, drying it in a stream of air at one temperature for 4 hours calcined from 400 ° C. The impregnated and calcined aluminum oxide was again with an aqueous kadmhim chloride solution. The 0.8 wt .-% of cadmium chloride were impregnated and then dried for 33 hours calcined in flowing air at a temperature of 600 ⁰ C. The resulting catalyst contained 1 part by weight of the calcined cadmium compound, 7.5 parts by weight of the calcined molybdenum compound and 92.5 parts by weight of aluminum oxide, calculated in each case as the oxide corresponding to the individual compound.

In connection with Example 20 using the catalyst described above in the same Proceed as in Example 1.

In connection with Comparative Example 6, the same procedure as in Example 20 was carried out.

however, the BB gas fraction is in direct contact with the catalyst without flowing through the water bath was brought so that the disproportionation took place in the absence of steam. The results are shown in Table 9.

Table 9 Disproportionate Disproportionate Isolation content __ Composition of the disproportionation Cs group Ct * fraction Example no. time r iiitgMiiiisatz in the Cs group product {%) 493 17.8 (Hours.) (%) (%) Propylene 50.1 14.0 23 21.0 100 3Z7 473 153 20th 33 20.0 100 353 40.6 24.6 43 173 100 36.6 4Z7 255 23 19.0 6Zl 33.2 43.9 26.1 Comparison 33 16.1 605 30.2 example 6 43 12 * 64.0 28.8

The Dreproportiionierungsproduki obtained according to comparison <. & E> Spiel contained a small amount of ethylene.

Examples 21 to

The process steps according to Example 20 were repeated three times, but for the preparation of the catalysts instead of cadmium chloride, lead nitrate (Example 21), bismuth trichloride (Example 22) and antimony trichloride (Example 23) were used.

The results are shown in Table 10.

Table .10

example Metal compound Disproportionate Disproportionate isopentic Composition of the disproportionate 50.9 C + 6 fraction No. tion time tioning salary in the production product (%) 513 203 sales Cs group 52.0 18.2 (Hours.) (%) W. 43.7 17.0 21 Lead nitrate 13th 12 ^ 100 Propylene Cs fraction 46.4 243 2.5 10.8 100 28.6 48.1 17.2 3.5 10.8 100 303 44.8 163 22nd Bismuth trichloride 1.5 18.4 96.1 31.0 49.0 26.1 2.5 16.9 100 31.8 46.0 21.1 3.5 15.7 100 36.4 20.1 23 Antimony trichloride 13th 16.0 100 35.4 2.5 13.8 100 29.1 3.5 13.3 100 293 33.9

Comparative example 7

The procedure was the same as in Example 22, except that the water bath was omitted. so that the disproportionation occurred without steam. The results are shown in Table 11.

Table 11

Disproportionation Disproportionation Isopemic content Composition of the disproportionation product Time sales in the Cs group (%) Propylene Cs fraction C + b fraction (Hours.) (%) (%)

13th 21.8 67.4 28.5 42.1 283 2.5 16.9 64.6 27.1 40.7 32.2 33 14.2 65.5 23.7 42.7 32.9

Comment:

The disproportionation product contained a small amount of ethylene.

Examples 24 and 25 and Comparative example 8

In connection with the examples 24 and 25 was obtained in the same manner as in Example 20, wherein the disproportionation over a period of 2.5 hours at temperatures of 300 ⁰ C

Table 12

(Example 24) and 350 ⁰ C (Example 25) and not at 250 ° C was carried out.

In connection with the Comparative Example 8 was obtained in the same manner as in Example 24, except that the disproportionation is carried out at 200 ⁰ C

The results are summarized in Table 12

Example no.

Disproportionation temperature

Disproportionation isopenlene content Composition of the disproportionation turnover in the Cs fraction product (%)

Propylene Cs fraction C + e fraction

24 300 25th 350 Comparison 200 example 8

19.6 12.9 25.8

Examples 26 and 27

983 100 85.7

333
28.8
163

53.6
583
25.9

123 123 573

1000 cnV / cm * catalyst / hour (Example 27) passed through where the volume information refers to the

The process steps according to Example 20 were based on 65 normal volumes. The disproportionation

repeated twice, wherein the BB-gas fraction through a water bath at flow rates of 300 cm ³ / cm ³ catalyst / hr. (Example 26) or

process was carried out in both Examples 26 and 27 for a period of 23 hours The results are summarized in Table 13

Table 13 Example no, flow rate Isooemengenate composition of the dispropomony

¹ SgZ * KSS- »·, - <·»

Propylene Cs-Fraction C -r ^ fraction

(cmVcin * - catalyst / hour)

300 1000

22.5 11.6

963 98.7

293

29, i

49Ji 51p

20.4 19.4

Examples 28 and 29

The procedure according to Example 20 was repeated twice, but using the temperatures of the water bath to which the disproportionate BB gas fraction was fed, 25 ° C (Example 28) or 60 ° C (Example 29); the BB gas fraction

Table 14

After flowing through the water, it contained steam in amounts of 3.1% by volume (Example 28) and 19.7% by volume (Example "BX ") based on the volume of the BB gas fraction fed to the dispnoportioning process. The planning time was 25 hours in both examples. The results are summarized in Table 14

example No.

Temperature of Water bath

Dampfgehah

(VoL-%) Composition of the disproportionation product (%)

Propylene Cs fraction C ^ b fraction

25th 60

Xl

19.7

18.5 18.0 100 100

30.1

503 51.2

19.4 173

Examples 30 to 37

The procedure of Example 1 was repeated eight times repeated, however, the catalyst prepared in a manner similar to Example 1 863 parts by weight Aluminum oxide, 1 part by weight of the calcined tin compound, calculated as tin oxide (SnOX 33 parts by weight κ. of the calcined cobalt compound, calculated as cobalt oxide (CoOX and 10 parts by weight of the calcined molybdenum compound, calculated as molybdenum oxide (MoO ₃ ), and the disproportionation process in those shown in Table 15

Temperatures and pressures took place The results are summarized in Abeüe 15 Table 15

example No.

Disproportionation

process

Pressure temperature

(kg / cm ^ G) ( ⁰ C)

Scheduling turnover Isopes content Composition of the disproportionate development in the C ^ FraktkMii product (%)

Propylene Cv fraction C + & - fraction

30th 2 31 2 32 2 33 3 34 3 35 3 36 4th 37 5

250 28j6 275 27Y 300 24.7 250 30.7 275 283 300 24.2 250 33J8 250 363

100 100 100 100 100 100 100 100

33 pounds 48.6 34.7 493 343 49.0 303 473 323 47.4 33.1 483 32J8 47.1 263 483

173 153

21.2 20.4 XSfi 20.1

24.7

Comparative example 9

According to the process described in US ^{Pat. No. I 1} S 3546 314, a catalyst was prepared from 91% by weight of silicon oxide and 9% by weight of tungsten oxide by impregnating a silicon oxide suitable for Katarysatorzwecke with an aqueous solution of ammonium metatungstate and then the Water has evaporated from it. The catalyst was calcined for about 4 hours at a temperature of 400 ° C. in a stream of air

A BB fraction gas consisting of ASJ % by weight isobutene, 16.4% by weight butene-2, 263% by weight butene-1, 1 ^% by weight isobutane, 7.1% by weight η-butane and 03% by weight of a mixture of propane, propylene, 13 Butadiene and propadiene, became disproportionate! the BB-Fraktk »n for 13 hours at a temperature of 300 ⁰ C and at atmospheric pressure with the catalyst as described above with a flow rate of 645cm ³ / cm ³ of catalyst-STD, calculated on volume standard, is brought into contact time te was virtually no Disproportionation takes place, ie after the end of the disproportionation process, only traces of isopentene could be found in the product.

Comparative example

10

The procedure was essentially the same as in Comparative Example 9, except that the

Disproportionation at a temperature of 550 ⁰ C took place. The disproportionation conversion was 45.7%, the proportion of isopentene in the Cs fraction was 67.9%, and the proportions of ethylene, propylene, the Cs fraction and the C ^ fraction in the disproportionation product were 11, 0%, 33JO%, 35.7% and 203%, respectively.

It follows that the proportion of the Cs fraction in the disproportionation product is low and that the proportion of isopentene in the Cs-Frakliou is also low is low. When using the known catalyst, the disproportionation product thus contains a large amount of undesirable by-products, while the yield of isopentene is only low.

Comparative Example 11

The procedure was essentially the same as in »Comparative Example 9, with one however, the BEi-Fraktioosgas let flow through a water bath, so that this gas with 0.6 Vol-% Water vapor, based on normal volume, was mixed before the fraction gas was mixed with the * catalyst in Contact was made. When the disproportionate tion process took place at a temperature of up to 300 ⁰ C, could be observed essentially no disproportionation effect. If the disproportionation took place at a temperature of 550 ^° C., the catalyst was deactivated quickly. The disproportionation product therefore contained only a trace of isopentene.

Claims (6)

Patent claims: 1. A process for the preparation of isopentene by catalytic disproportionation of a hydrocarbon mixture containing isobutene and η-butene, characterized in that the hydrocarbon mixture is mixed with a catalyst which is produced by introducing a molybdenum compound and at least one further cobalt, tin, silver, cadmium, Lead, bismuth or antimony compound on an alumina support and subsequent calcination is made and that of 5-20% of the calcined molybdenum compound and 0.5-10% of the calcined additional metal compound, based on the weight of the aluminum support and based on the corresponding oxides , consists, in the presence of 0.1-25% water vapor, based on the volume of the hydrocarbon mixture and calculated on normal volume, at a flow rate of 50-2000 cm ³ / hour, calculated on normal volume, per cm ^{3 of} the catalyst in contact and at a temperature of 220 ° -380 ⁰ C and pressure ♦ INEM disproportionated between normal pressure and 10 kg / cm ² and separates the isopentene formed from the reaction mixture. 2. The method according to claim 1, characterized in that one is in the presence of a catalyst disproportionate, the 1-5% calcined additional metal compound, based on weight of the aluminum oxide carrier and calculated on the corresponding oxide. 3. The method according to claim 1, characterized in that in the presence of an amount of 0.2-10% water vapor, calculated based on the volume of the hydrocarbon mixture i-nd to normal volume size, disproportionate 4. The method according to claim 1, characterized in that that one disproportionated at a temperature of 230-350 ° C. 5. The method according to any one of claims 1 to 4, characterized in that one is in the presence a catalyst disproportionated at a temperature of 100-300 ° C with an inert gas, which, calculated to normal volume, contains 0.1-25% steam. 6. The method according to claim 1, characterized in that the hydrocarbon mixture is brought ^{into contact with the catalyst at a flow rate between 100-1000 cm 3} / cm ³ catalyst / hour.